The attributes of gender selection in animal breeding and the ability to form an agro-technical infrastructure around it that will improve performance is already well established in cultured animals such as cattle, poultry and fish (De Vries (2008); Correa et al., (2005) and Beardmore et al., (2001)). Crustaceans' aquaculture still predominantly uses heterogenic populations that suppress most sexual dimorphic growth patterns. When segregated, crustaceans demonstrate enhanced growth rates as energy is allocated towards growth rather than towards gonad maturation and other sexual activities related to reproduction. Predominantly, crustacean aquaculture is exclusively depended on nurseries & hatcheries for juvenile supply as reproduction is not part of the grow-out stage in the farm and allocation of energy towards it is undesirable. Thus, culturing of mono-sex populations, either all-male or all-female, produces higher yields and greater commercial value. Although in some crustacean species all-male populations generate higher yields under extensive culturing conditions, several studies suggest (Gopal et al., (2010) and Otoshi et al., (2003)) that under intensified farming conditions and in most decapod crustacean species farmed today it is females that are economically more favorable. In an all-female population under commercial conditions, final sizes at harvest are highly uniform yielding up to 35% higher production value than all-males. Furthermore, it appears that the separation from the males reduces aggressiveness and stress, decreases cannibalism, delivers a higher homogeneity in marketing size and most importantly enables higher stocking rates.
Sexual differentiation and the development of secondary sexual characteristics are controlled by different mechanisms across evolution. In vertebrates and some invertebrate groups, these processes are under the control of sex hormones. Given the recent confirmation that insects probably have no sex hormones, the agents responsible for the sexual maturation of arthropods remain under debate. Crustaceans that are evolutionary close to insects possess an androgenic gland (AG) which is responsible for male sexual differentiation. Interestingly, in some crustaceans, endocrine regulation of sexual differentiation precedes the phenotypic appearance of this secondary external feature.
The role of the AG in male sexual differentiation was demonstrated in several crustacean species by observing primary and secondary sex characteristics after AG removal or transplantation. In the amphipod Orchestia gamarella, bilateral AG ablation diminished spermatogenesis and obstructed the development of secondary male characteristics. In Macrobrachium rosenbergii, a fully functional sex reversal from males to Neo-females and from females to Neo-males was achieved by surgical bilateral AG ablation and transplantation, respectively.
To date, no effective technology for production of female mono-sex decapod crustacean populations is achieved. There is still a need for efficient, cost-effective and safe methods for production of mono-sex all-female populations of decapod crustaceans.